UPDATE [08-May-08]: The links to the american and european firmware were changed due to bandwidth problems. The previous links will no longer work.

UPDATED 08-May-08

DO NOT FORMAT FROM YOUR COMPUTER IN RECOVERY MODE!!!! EVER!!!! DON'T EVEN THINK ABOUT DOING THAT!!!!! DON'T EVEN THINK ABOUT THINKING ABOUT DOING THAT!!!!!! IT WILL MOST LIKELY BRICK YOUR PLAYER_OUT OF REPAIR!!!!

Also, despite what you might hear, it is ok to put a .mi4 and .rom in the 16MB recovery mode thing, just NOT ANYTHING ELSE.
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make sure you have backups of your music

enter recovery mode. if you dont know how to, you just need to put the hold switch on so you see orange, hold down the record button and turn the player on. keep holding the record button until you see:
Welcome to recovery mode
Please connect USB cable

plug your player in

open notepad, and save a blank text document named "sansa.fmt" and drag that into the 16MB recovery mode thing

NOTE: this will force-format the player which will delete everything and install the newest firmware and bootloader.

hope this helps!

also, i attached my ultimate fix for quick reference so you dont have to come to this thread when you have a problem, and i attached the sansa.fmt thing in a compressed folder. it actually has the .fmt extension, which it has to have, i.e. it cant be sansa.fmt.txt. just unzip, and drag to the player when stated in the steps

How to get rid of the "synchronize to continue music subscription" message if it just appears out of nowhere on your player- this fixed mine when it gave me that message:

delete the STORE.HDS file in the system/wmdrmpd directory of your sansa (optional)